The major objective of this study is to develop a method for examining the timescale and mechanism of very short-lived interactions in solution. The method will be applied to investigations of the molecular dynamics of hydrogen bonding and transient complex formation. Solvent-solute interactions in liquid solutions are examined by observing the change in the relaxation times of solvent nuclei in the pesence of paramagnetic solutes. The interaction of these nitroxide spin labels with solvent molecules is modulated by the relative motion of the two species. Determination of the timescale of the interaction is accomplished by isolating the spectral density function in the coupling strength. This provides the rate of formation and breaking of the hydrogen bond between the solvent and solute molecules and characterizes the distance of approach of the two molecules.